QQuickStyle: fix random crashes accessing deleted QQuickPopupItem

Don't access QQuickPopupItem while being destroyed. The popup item is
deleted in QQuickPopup destructor, which is the parent of QQuickStyle
that is attached to a popup. We don't need to remove the listener in
this case.

Change-Id: I0e0dba533b3b1299eb0d266c92f3070bb193c6c9
Reviewed-by: J-P Nurmi <jpnurmi@theqtcompany.com>

2 files changed, 8 insertions, 15 deletions

diff --git a/src/controls/qquickstyle.cpp b/src/controls/qquickstyle.cpp
index c38950d8..76cb24cc 100644
--- a/src/controls/qquickstyle.cpp
+++ b/src/controls/qquickstyle.cpp
@@ -145,14 +145,20 @@ static QList<QQuickStyle *> findChildStyles(const QMetaObject *type, QObject *ob
 
 QQuickStyle::QQuickStyle(QObject *parent) : QObject(parent)
 {
-    QQuickItem *item = parentItem();
+    QQuickItem *item = qobject_cast<QQuickItem *>(parent);
+    if (!item) {
+        QQuickPopup *popup = qobject_cast<QQuickPopup *>(parent);
+        if (popup)
+            item = popup->popupItem();
+    }
+
     if (item)
         QQuickItemPrivate::get(item)->addItemChangeListener(this, QQuickItemPrivate::Parent);
 }
 
 QQuickStyle::~QQuickStyle()
 {
-    QQuickItem *item = parentItem();
+    QQuickItem *item = qobject_cast<QQuickItem *>(parent());
     if (item)
         QQuickItemPrivate::get(item)->removeItemChangeListener(this, QQuickItemPrivate::Parent);
 
@@ -174,17 +180,6 @@ QSharedPointer<QSettings> QQuickStyle::settings(const QString &group)
     return QSharedPointer<QSettings>();
 }
 
-QQuickItem *QQuickStyle::parentItem() const
-{
-    QQuickItem *item = qobject_cast<QQuickItem *>(parent());
-    if (!item) {
-        QQuickPopup *popup = qobject_cast<QQuickPopup *>(parent());
-        if (popup)
-            item = popup->popupItem();
-    }
-    return item;
-}
-
 QList<QQuickStyle *> QQuickStyle::childStyles() const
 {
     return m_childStyles;
diff --git a/src/controls/qquickstyle_p.h b/src/controls/qquickstyle_p.h
index c5bfed0f..02ee667a 100644
--- a/src/controls/qquickstyle_p.h
+++ b/src/controls/qquickstyle_p.h
@@ -72,8 +72,6 @@ public:
 protected:
     void init();
 
-    QQuickItem *parentItem() const;
-
     QList<QQuickStyle *> childStyles() const;
 
     QQuickStyle *parentStyle() const;